Independently rotated pneumatic rock drill

ABSTRACT

An independently rotated, muffled pneumatic rock drill comprising an impact mechanism housing in which an impact mechanism and a rotation motor are located and in which housing also is enclosed an air volume into which the exhaust air from both the impact mechanism and the rotation motor is discharged. The rotation motor has an exhaust pipe of a tuned length.

United States Patent [151 3,659,657 Ahlberg et al. [4 May 2, 1970 [54] INDEPENDENTLY ROTATED [56] References Cited PNEUMATIC ROCK DRILL UNITED STATES PATENTS m1 muchvicwrAhIbewGWerI-"d $12323??? $51323 311,232::::i::::""::;::::::: "3131325182 Ekwall, both of Nacka; 3,385,378 5/1968 Weberetal. 173/105 Ronald Lindqvlst, Tumba, all of Sweden Assignee: Atlas Copco Aktlebolag, Nacka, Sweden Filed: Oct. 1, 1970 Appl. No.: 77,233

US. Cl. ..l73/l05 Int. Cl ..B25d 9/00 Field ofSearch.... .....l73/105,106,l07, 108, 109,

Primary Examiner-James Leppink Attorney-Bauer and Goodman [5 7] ABSTRACT An independently rotated, muffled pneumatic rock drill comprising an impact mechanism housing in which an impact mechanism and a rotation motor are located and in which housing also is enclosed an air volume into which the exhaust air from both the impact mechanism and the rotation motor is discharged. The rotation motor has an exhaust pipe of a tuned length.

4 Claims, 2 Drawing Figures INDEPENDENTLY ROTATED PNEUMATIC ROCK DRILL This invention relates to an independently rotated pneumatic rock drill. The main object of the invention is to provide a muffled rock drill of the above mentioned type in which both the impact mechanism and the rotation motor are effectively muffled.

Other objects of the invention will be apparent from the following detailed description and drawing wherein:

FIG. 1 is a vertical elevational view, partly in section, of a rock drill embodying the invention.

FIG. 2 is an enlarged cross sectional view taken along line 11- in FIG. 1.

Referring to the drawing, 1 designates an impact mechanism housing which contains an impact mechanism 2. The impact mechanism comprises a hammer piston 3 which is slidably mounted in the housing 1. The impact mechanism 2 also comprises a cylinder liner 4 that surrounds the rear end of the hammer piston 3.

The cylinder liner 4 is provided with air exhaust means which may consist of rows of small diameter holes 5. This atrangement has a primary muflling effect in that the hammer piston under its forward movement towards the neck of the drill steel 11 successively uncovers one row after the other, whereby the pressure in the cylinder is successively lowered. Thus, the air pressure shocks from the impact mechanism are smoothed out.

The impact mechanism housing 1 also contains a separate rotation motor 6. The rotation motor 6 rotates the drill steel 11 independently of the impact mechanism by means of a reduction gear and a chuck bushing (not shown in detail). The rotation motor is a vane type motor provided with an exhaust pipe 7 at its rear end. The exhaust pipe 7 has a length that is tuned to the wavelength of the exhaust sound in order to avoid resonances and to effect a primary silencing of the rotation motor.

Within the impact mechanism housing 1 is enclosed an air volume 8 surrounding the rotation motor 6 as well as the cylinder liner 4 (see FIG. 2). The air exhaust from both the impact mechanism and the rotation motor are discharged into this air volume 8, whereby -a secondary silencing is effected in that the remaining air pressure shocks are effectively absorbed by the air volume.

Further, the impact mechanism housing 1 is provided with a mounting surface 9 for mounting the rock drill on aslide (not shown). The mounting surface is so located on the housing 1 that the rock drill will be mounted on the slide with the rotation motor inside the impact mechanism. By locating the impact mechanism outside the rotation motor a very short distance is obtained between the outermost surface of the rock drill and the drill steel. That makes it possible to drill a hole close up to a wall or a roof. I

The impact mechanism housing 1 is moreover provided with air outlet openings 10 which extend through the mounting surface 9 and direct the exhausted air towards the feed mechanism (not shown). This arrangement is advantageous in that the rock drill guides and feed mechanism are blown cleaned and lubricated by the exhausted air.

We claim:

1. An independently rotated pneumatic rock drill comprising an impact mechanism housing, a hammer piston slidably mounted in the housing, a cylinder liner surrounding the rear end of the hammer piston and provided with air exhaust means, a separate rotation motor located within the housing and means defining an air volume enclosed within the housing and surrounding the cylinder liner as well as the rotation motor, into which air volume the exhaust air from both the impact mechanism and the rotation motor is discharged.

2. The muffled pneumatic rock drill of claim 1, wherein the roation motor is a vane-type motor provided with an exhaust pipe the length of which is tuned to the wavelength of the exhaust sound to avoid resonances.

3. The muffled pneumatic rock drill of claim 1, wherein the impact mechanism housing is provided with a numberof exhaust openings through which the exhausted air is directed towards the feed mechanism.

4. The muffled pneumatic rock drill of claim 1, wherein the air exhaust means of the cylinder liner comprises circumferential rows of small diameter holes.

0 I t i l UNKTED STATES PATENT OFFICE CERTIFZCATE CGRRECTEGN Patent No. 3 i 657 Dated y 2 1972 Inventofls) Erik Johan Victor Ahlberg et al.

It is certified that error appears in the above-identified patent and that; said Letters Patent are hereby corrected as shown below: I v

In theupper right hand portion of the cover page the date of grant of the paterit should read es follows [45] May 2 x1972" I Signed and sealed this 26th day of December 1972.

(YSEALJ) Attest: EDWARD PLFLETCHERJR. ROBER RT TOTTSCHALK Attesting Officer Gommlssloner of Patents FORM PC1-1050 (10-69) 

1. An independently rotatEd pneumatic rock drill comprising an impact mechanism housing, a hammer piston slidably mounted in the housing, a cylinder liner surrounding the rear end of the hammer piston and provided with air exhaust means, a separate rotation motor located within the housing and means defining an air volume enclosed within the housing and surrounding the cylinder liner as well as the rotation motor, into which air volume the exhaust air from both the impact mechanism and the rotation motor is discharged.
 2. The muffled pneumatic rock drill of claim 1, wherein the roation motor is a vane-type motor provided with an exhaust pipe the length of which is tuned to the wavelength of the exhaust sound to avoid resonances.
 3. The muffled pneumatic rock drill of claim 1, wherein the impact mechanism housing is provided with a number of exhaust openings through which the exhausted air is directed towards the feed mechanism.
 4. The muffled pneumatic rock drill of claim 1, wherein the air exhaust means of the cylinder liner comprises circumferential rows of small diameter holes. 